Clarify companion binding ownership

docs/consumers/README.md

@@ -38,8 +38,9 @@ Start with one file, then choose the tasks your application needs:
 - Use `LoadLayered` when several inputs should supply lower-priority defaults
   beneath the main source. Each underlay group combines its inputs strictly.
   Each [`Input`](../../layered.go) owns its source, filesystem, destination, and
-  import choice. Main-relative bindings and overlay context selection are
-  available in [`LayeredOptions`](../../layered.go).
+  import choice. Set `Input.MainRelative` on a companion underlay to use the
+  main input's filesystem context. Overlay context selection belongs to
+  [`LayeredOptions`](../../layered.go).
 - Load-wide rules belong to [`Options`](../../lifecycle.go) or
   [`LayeredOptions`](../../layered.go): the application definition (including
   version policy), import defaults, and explicit overrides. These do not turn

docs/internal/imports.md

@@ -20,10 +20,12 @@ patterns to discovered names, and form a set union of matching candidates across
 overlapping roots. Exclusions are applied as set difference after discovery and
 candidate normalization. They do not suppress discovery or resource errors.
 
-Layered assembly passes the resolved main context to underlay acquisition,
-replacing tier-local identity state. Contextless bindings prepare declaration
-policies and assemble the declaring payload without opening access or inventing
-selection evidence. Selected contexts use the normal acquisition and handle path.
+Layered assembly passes the resolved main context to underlay acquisition.
+Derived inputs retain the main's filesystem location and namespace. The
+receiving tier supplies its own host token and tracks repeated sources.
+Contextless bindings prepare declaration policies and assemble the declaring
+payload without opening filesystem access or recording selection evidence.
+Selected contexts use the existing acquisition and handle lifecycle.
 
 Directory traversal tracks canonical directories on the active traversal path.
 It adds an identity when descending and removes it when the frame is popped, so

docs/roadmap/remediation.md

@@ -96,6 +96,8 @@ before reaching overlay selection.
 
 ## Finding 4 — Supporting documentation misstates binding ownership
 
+**Status** — Complete. The consumer guide identifies Input.MainRelative, and the internal guide describes the receiving tier’s identity bookkeeping.
+
 **Priority P3.** The consumer guide locates main-relative bindings in
 `LayeredOptions`, but a companion binds through `Input.MainRelative`.
 The import internals guide says passing the main context replaces tier-local